Chemical Resistance – Fatigue Resistance – Electrical Insulation – Consumer Grade
form futura centaur white polypropylene.
Overview
Polypropylene is an extremely popular material spanning countless industries. It is a material that is widely accepted and has great properties across the board for a low cost plastic. It is not the most popular among 3D printing enthusiasts because it does take some practice and experience to print successfully.
Chemical Resistance
Polypropylene is used heavily in chemical wet process equipment used to make circuit boards and semiconductors because of its strong resistance to many of the acids used in their processes.
Fatigue Resistance
Polypropylene is known for its ability to have “living hinges” that last. These are the hinges you might see on a plastic food container.
Electrical Insulation
Dielectric constant @1kHz: 2.2-2.6
Dielectric strength kV mm^-1: 30-40
Dissipation factor @1MHz: 0.0003-0.0005
Surface resistivity Ohm/sq: 10^13
Volume resistivity Ohm/cm: 10^16-10^18
Material Properties
Density: 0.905g/cm^3
Mechanical Properties
Tensile Strength at yield: 30 MPa
Elongation at Yield: 8%
Modulus of elasticity in tension: 1600 MPa
Shore Hardness: 70
Thermal Properties
Glass transition temperature: -18C
Crystalline melting point 165C
Service temperature (Short term): 130C
Service temperature (Long term): 100C
Coefficient of thermal expansion: 17×10-5K
Specific Heat: 1.7 J/(g*K)
Coefficient of thermal conductivity: .22 W/(K*m)
Consumer Grade
Polypropylene is used in a wide variety of products and packaging. It is used especially in food packaging. While 3D printed parts themselves are often not considered consumer grade, polypropylene is a more acceptable choice for many people since it is so common and has generally good properties.
3D Printing Difficulty
Moderate
My experience with polypropylene as a 3D printing material has been somewhat mixed. You can get high quality prints in a repeatable fashion if you dial in your model and your settings. Temperature is especially important since polypropylene warps at any chance it gets. It is not required to have an enclosure but one is definitely recommended (and makes life easier). I personally just have a fireproof enclosure but do not actively heat it. The heated build plate and nozzle heat it to about 100 F. It more importantly protects your printer from drafts from open windows or air conditioners that seems to pry the part off of the build plate and create a major warp or completely ruins a print.
Pros
- Excellent Layer Adhesion
- Relatively Low Printing Temperature
- Can Be Printed On Almost Any 3D Printer
Cons
- Prone To Warping
- Hygroscopic (Absorbs Moisture)
- Poor Build Plate Adhesion
Build Plate Adhesion
One of the most critical things to do to have a successful print is to have the correct build plate conditions. Polypropylene doesn’t like to adhere to much besides itself. The easiest way to get good build plate adhesion is to put some packing tape on your build plate. Most packing tapes are made from PP and work just fine. Take care to make sure you don’t leave air bubbles underneath the tape as they will show up in the part. There are also thin sheets of PP available to stick on your build plate and adhesives specifically for 3D printing PP.
